Pyrazinamide (or pyridinecarboxamide) is an antituberculosis agent which acts bactericidally against intracellular tubercle bacillus (M. tuberculosis), in particular. However, pyrazinamide has no antibacterial activity against other acid-fast bacteria such as M. avium and M. intracellulare and, therefore, is not expected to be effective against the M. avium complex which is becoming a more and more serious problem with the spread of AIDS. Therefore, even if acid-fast bacteria are detected in the patient by the Ziehl-Neelsen stain-microscopic examination of the sputum, no therapy can be immediately instituted and because of the need for differentiation as to whether the infection is associated with M. tuberculosis or due to the M. avium complex, a waiting time of several weeks is necessary for the institution of a therapy.